Naturally radioactive elements

1) have unstable nuclei
2) give off alpha, beta, or gamma rays
3) decay into another element
4) all of these

This did i unseated, sorry

The sun's gravitational pull is weaker on the planets that are closer to it, i think.

Each student aligns the edge of the object with the left edge of the ruler as shown above. all four students read the ruler with a measurement of 4.6 cm. which statement describes the data they collect? i believe the answer is: the data have poor precision and poor accuracy because of a systematic error.

Bis the